1. Field of the Invention
This invention relates to medical instruments for electrical application to the body. More particularly, this invention relates to improvements in medical ablation catheters.
2. Description of the Related Art
Radiofrequency (RF) ablation of the heart is a procedure that is widely used to correct problematic cardiac conditions, such as atrial fibrillation. The procedure typically involves insertion of a catheter having an electrode into the heart, and ablating selected regions within the heart with RF energy transmitted via the electrode. Capacitive effects can interfere with electrophysiologic signals when power is transmitted to an ablation electrode.
U.S. Patent Application Publication No. 2014/0155758, entitled Low Capacitance Endoscopic System proposes an endoscopic system having distal sensors, in which the capacitance of the sensor system relative to earth ground maintains current leakage to a level that meets a cardiac float rating. During sensing, power can be transmitted to the sensor via a power transmission line from a ground-referenced power source, and data signals can be transmitted to the sensor via a data signal transmission line from a processing circuit at a proximate end of the endoscopic shaft. In response to electromagnetic interference proximate the remote surgical site, induced voltages level changes in the data signal transmission line and the power transmission are substantially equalized.
Arrangements wherein an ablation electrode in the catheter is in proximity to microelectrodes are known, for example, from U.S. Patent Application Publication No. 2013/0190747, which discloses an ablation catheter having a tissue ablation electrode and a plurality of microelectrodes distributed about the circumference of the tissue ablation electrode and electrically isolated therefrom. The plurality of microelectrodes define a plurality of bipolar microelectrode pairs. In this arrangement mapping microelectrodes are disposed near the ablation tip electrode to allow the center of mapping or pacing to be in substantially the same location as the center of ablation. It is asserted that the microelectrodes can advantageously provide feedback on electrode contact and tip electrode orientation within the heart.